1. Field of the Invention
The present disclosure relates to a belt conveyance apparatus for rotationally moving an endless belt stretched by a plurality of stretching members, and an image forming apparatus including the belt conveyance apparatus, such as a printer and a copying machine employing an electrophotographic process.
2. Description of the Related Art
Some of conventional image forming apparatuses, such as printers and copying machines employing the electrophotographic process, utilize a belt conveyance apparatus for rotationally moving an endless belt stretched by a plurality of stretching members. Such belt conveyance apparatuses have a problem that, when rotationally moving the belt, the belt may shift toward one end in the width direction (the direction approximately perpendicularly intersecting with the rotational direction of the belt).
Japanese Patent Application Laid-Open No. 11-079459 discusses a technique for restricting a belt from moving in the width direction to adjust the lateral movement of the belt. This technique uses a drive roller and a driven roller for stretching the belt, and inclines the driven roller with respect to the drive roller around a shaft at the center in the width direction. Specifically, a frame for supporting both ends of a shaft of the driven roller is rotatable around a rotating shaft provided on the outer circumferential surface of the belt.
When the belt moves toward one end, the tension applied from the belt to a stretching roller at one end becomes larger than the tension at the other end. When the tension is unbalanced in this way, the one end of the stretching roller is pressed by the belt and accordingly the stretching roller tends to move so as to get away from the inner circumferential surface of the belt. Thus, the one end of the frame is lowered and the other end thereof is raised around the rotating shaft. As a result, the driven roller inclines with respect to the drive roller so as to move the belt toward the other end.
The technique discussed in Japanese Patent Application Laid-Open No. 11-079459 inclines the driven roller with respect to the drive roller to adjust the lateral movement of the belt, and therefore needs to rotate the frame supporting the shaft of the driven roller, around the rotating shaft on outer circumferential surface of the belt. This causes a problem of a complicated configuration.